Shank stiffener



A118 16, 1938. G. E. MusEBEcK 2,126,913

' sHANK STIFFNER Filed April 12, 193'? ATTORNEY-5.

Patented Aug. 16, 1938 iiNi'rEo STATES PATENT GFFIQE SHANK STIFFENER poration Application April 12, 1937, Serial No. 136,327

Claims.

This invention relates to a shank stiffener for shoes and particularly to a stiiener designed to give a maximum of support to the fifth metatarsal bone and the outer weight-bearing part 5 of the foot.

In walking barefoot, the fifth metatarsal bone lies flat on the ground. It supports the wedge bones across the instep and controls the heel and ankle bones as well as the long inner arch of the foot. The base or rearward end of this bone lies directly beneath the cuboid bone which is in turn the keystone of the outer weight-bearing arch of the foot. When the heel of the foot is lifted above the ground by a shoe heel of any height, the base of the fifth metatarsal loses its Contact with the ground and unless properly supported by the shoe it is pressed downwardly by the weight of the body away from its normal position relative to the other bones of the foot.

The bones of the instep likewise are pressed into abnormal positions and collapse of the entire foot may follow.

One object of the present invention is to provide normal support for this important bone.

This is accomplished by making the outer portion of the stiffener of much greater strength and stiffness than the remainder thereof.

.Another object of the invention is to prevent buckling of the shoes at the rear end of the stiiener. Shank stieners ordinarily extend only a short distance to the rear of the heel breast, otherwise they interfere with the nails or pegs used to secure the outsole and heel to the insole at the rearward portion of the foot. There is, therefore, a tendency for the insole and outsole to be flexed at the rear edge of the stiffener which may eventually result in a permanent set in an unnatural position. This ilexure is known as buckling. To overcome the tendency to buckle, the stiffener is made with a long, narrow, rearward extension which is preferably a part of a reenforcing piece separate from the stiifener proper and which is shaped so as not to interfere with the nails or pegs used in this region of the shoe.

tension to the insole or outsole, or both. When so secured, the extension effectively prevents buckling.

Other objects and features of the invention will be understood from the accompanying drawing and the following description and claims.

Fig. l is a bottom View of the insole of a shoe together with a preferred form of the shank stiffener in their proper relative positions. Fig. 2 is a sectional view of the shank stiifener taken on Means are provided for securing this exthe line 2-2 of Fig. 1. Fig. 3 is a similar sectional view taken on the line 3-3 of Fig. 1. Fig. 4 is a side View of the shank stiffener in place, showing in broken lines the relative positions of the bones of the foot and the outsole, 5 insole and heel of a shoe.

In the preferred form of the invention shown by way of illustration in the drawing, the stiffener includes a plate I!! of relatively thin an-d flexible metal, such as steel. In Fig. l the stiff- 10 ener is shown resting on the undersurface of an insole I I to show its proper relative position with respect to the insole. The plate I0 projects forwardly beneath the metatarsal bones I2 and eX- tends rearwardly through the shank portion and 15 somewhat beyond the heel breast I3. The `portion of the plate beneath the metatarsal bones indicated at I4 is upwardly curved, as best seen in Fig. 2, to provide support for the metatarsal arch of the foot.

The outer edge I5 of the plate II) substantially parallels the outer edge of the outsole I I. Adjacent to the edge I5 there is formed in the plate Ill a depression or groove I6 within which there is secured a reenforcing member I'I, preferably 25 triangular in cross section as shown in Fig. 3. This reinforcing member extends from a point beneath the head I8 of the fth metatarsal bone rearwardly beneath the fth metatarsal and the cuboid bone I9. The member Il is provided 30 with an extension 20 which is flattened, as best seen in Fig. 4, and which extends substantially to the rear edge of the insole I I. Said extension is provided with an opening 2l adapted to receive a tack or nail for securing the same to the insole 35 II or outsole 22, as may be desired.

The construction of the stiffener as just described provides a relatively flexible support for the metatarsal arch and the inner longitudinal arch of the foot and at the same time gives a 40 substantially rigid support for the important fth metatarsal bone and the weight-bearing outer arch formed by the fifth metatarsal, the cuboid and the os calsis 23. This rigid support provides the equivalent of normal ground support, 5 even though the heel may be raised substantially above the ground level. It thus prevents the foot ills often caused by the sagging of the base 24 of the fth metatarsal. The extension 20 of 50 the reenforcing member I'I at the same time prevents undue flexing of the insole and outsole at the rear edge of the plate Ill and thus prevents the buckling of the shoe at this point, The form of the extension 20 is such that it will not inter- 55 fere with nails or pegs used in securing together the insole and outsole.

The foregoing specication describes in detail a preferred form of the invention, the details of which may be varied by those skilled in the art without departing from the scope of the invention as dened by the appended claims.

The invention claimed is:

1. A shank stiffener for shoes including a plate of relatively flexible metallic material extending forwardly beneath the metatarsal arch of the foot and rearwardly through the shank portion to the rear of the heel breast, and a piece of relatively stii reenforcing material secured thereto and extending from a point beneath the fifth metatarsal bone of the foot, adjacent to and substantially parallel with the outer edge of said plate to a point beneath thegheel of the foot, saidV reenforcing piece extending beyond the rear of said plate and having provision for securing the extended portion to other portions of the shoe.

2. A shank stiiener for shoes including a plate of relatively flexible metallic material extending forwardly beneath the metatarsal arch of the foot and rearwardly through the shank portion to the rear of the heel breast, and a piece of relatively stiff reenforcing material secured thereto and extending from a point beneath the fth metatarsal bone of the foot, adjacent to and substantially parallel with the outer edge of said plate to a point beneath the heel of the foot, said reenforcing piece having a flattened extension beyond the rear of said plate and said extension having an opening therein for the receipt of securing means. 3. A shank stifener for shoes including a plate of relatively flexible metallic material extending forwardly beneath the metatarsal arch of the foot and rearwardly through the shank portion to the rear of the heel breast, said plate having a longitudinal groove in the upper surface thereof eX- tending from a point beneath the fth metatarsal bone of the foot, adjacent to and substantially parallel with the outer edge of the plate to the rear thereof, and a piece of relatively stiff reenforcing material inset in said groove and secured to said plate, said reenforcing piece extending V beyond the rear of said plate and having provision for securing the extended portion to other portions of the shoe.

4. A shank stiffener for shoes including a plate of relatively flexible metallic material extending `forwardly beneath the metatarsal arch of the foot and rearwardly through the shank portion to the rear of the heel breast, said plate having a longitudinal groove in the upper surface thereof extending rom a point beneath the fifth metatarsal bone ofthe foot, adjacent to and substantially parallel with the outer edge of the plate to the rear thereof, and a piece of relatively stiff reenforcing material inset in said groove and secured to said plate, said reenforcing piece having a flattened extension lbeyond the rear of said plate and said extension having an opening therein for the receipt ofv securing means.

5. A shank stiiener for shoes extending forwardly beneath the metatarsal bones of the foot and rearwardly beneath at least a portion of the heel and having greater stiffness along the outer edge beneath the fth metatarsal and cuboid bones than beneath the remainder of the foot.

GEORGE E. MUSEBECK. 

